The invention lies in the field of engineering and relates in particular to fluid valves and hydraulic or pneumatic pump systems which are controlled by way of such valves.
Valves are known in a variety of embodiments for opening and for closing fluid conduits or for the control of hydraulic and/or pneumatic circuits. Such valves differ on account of their loading ability, by the speed of the response or of the actuation possibility, the sealedness, the pressure loadability, and by the number of switching operations which may be carried out without significant wear. The design of such valves with regard to the material selection, the fashion as well as the allowable manufacturing tolerances depends on the individual demands.
With fluid circuits in the pressure range of a few atmospheres excess pressure, sliding valves for example are actuated, with which a slide is translatorily movable in a bore of a connection block and, by way of recesses which are provided in the slide, connects different openings or channels of the connection block to one another depending on the slide position. One may selectively subject different fluid conduits to pressure by way of such a valve.
The play tolerance with the dimensions of such a slide in relation to the bore, in which it moves may be of a magnitude for example of hundredths of millimeters, in order to avoid unallowable leaks. An air cushion effect may form with the movement of such a slide, given a correct dimensioning of the tolerances, and this effect avoids direct contact and wear.
Moreover, a rotary slide valve arrangement for the pneumatic control is known from the German patent document DE 10 2006 011 580 B3 of the company Numatics GmbH, which serves for the control of compressed air and envisages a control slide (control valve) which is rotatable in a cylinder bore and which may be rotated and driven, wherein the control slide comprises surface grooves or inner channels which connect transverse bores in the connection block to one another or separate them from one another, depending on the rotation position. Thereby, a cylinder gap between the cylinder bore in the connection block and the control slide is dimensioned such that a low-friction mounting is given according to the principle of an air bearing.
It is clear from the cited patent document, that in each case different channels in the connection block, which are arranged at different axial heights in relation to the rotation axis of the slide, are connected to one another by way of the slide.
The task often arises of switching pneumatic circuits in a manner such that on the one hand the pneumatic resistance of the conduits and valves is minimised in the different switch position and that on the other hand as constant as possible pneumatic flow resistances are maintained at different switch positions.
A system with two membrane heart pumps as well as a switch-over valve is known from U.S. Pat. No. 5,232,434.
A switch-over valve is known from WO 89/01600 A2, with which channels are switched by way of a control pin in a hollow cylinder. For switching between several channels which lie at different axial heights in the hollow cylinder, a switch channels is used, which in the control pin runs from a first axial position to a second axial position. This entails a design of the control pin which is complex and difficult to manufacture.
It is the object of the present invention, to provide a valve which combines quick and efficient switch-over possibilities with an as minimised as possible flow resistance and with a simple design construction of the valve.